Effects of heavy metals on aerobic denitrification by strain Pseudomonas stutzeri PCN-1

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• 作者：Mengyao Gui ; Qian Chen ; Tao Ma ; Maosheng Zheng…
• 关键词：Heavy metals ; Aerobic denitrification ; Pseudomonas stutzeri ; Gene expression ; Sensitivity
• 刊名：Applied Microbiology and Biotechnology
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：101
• 期：4
• 页码：1717-1727
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Microbiology; Microbial Genetics and Genomics; Biotechnology;
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-0614
• 卷排序：101

文摘

Effects of heavy metals on aerobic denitrification have been poorly understood compared with their impacts on anaerobic denitrification. This paper presented effects of four heavy metals (Cd(II), Cu(II), Ni(II), and Zn(II)) on aerobic denitrification by a novel aerobic denitrifying strain Pseudomonas stutzeri PCN-1. Results indicated that aerobic denitrifying activity decreased with increasing heavy metal concentrations due to their corresponding inhibition on the denitrifying gene expression characterized by a time lapse between the expression of the nosZ gene and that of the cnorB gene by PCN-1, which led to lower nitrate removal rate (1.67∼6.67 mg L−1 h−1), higher nitrite accumulation (47.3∼99.8 mg L−1), and higher N₂O emission ratios (5∼283 mg L−1/mg L−1). Specially, promotion of the nosZ gene expression by increasing Cu(II) concentrations (0∼0.05 mg L−1) was found, and the absence of Cu resulted in massive N₂O emission due to poor synthesis of N₂O reductase. The inhibition effect for both aerobic denitrifying activity and denitrifying gene expression was as follows from strongest to least: Cd(II) (0.5∼2.5 mg L−1) > Cu(II) (0.5∼5 mg L−1) > Ni(II) (2∼10 mg L−1) > Zn(II) (25∼50 mg L−1). Furthermore, sensitivity of denitrifying gene to heavy metals was similar in order of nosZ > nirS ≈ cnorB > napA. This study is of significance in understanding the potential application of aerobic denitrifying bacteria in practical wastewater treatment.